1. Field of the Invention
The invention relates generally to handheld electronic devices and, more particularly, to a variable speed input apparatus for a handheld electronic device. The invention also relates to a method of enabling input to a handheld electronic device using a variable speed input device.
2. Description of the Related Art
Numerous types of handheld electronic devices are known. Examples of such handheld electronic devices include, for instance, personal data assistants (PDAs), handheld computers, two-way pagers, cellular telephones, and the like. Such handheld electronic devices are generally intended to be portable and thus are relatively small.
Many handheld electronic devices include and provide access to a wide range of integrated applications, including, without limitation, email, telephone, short message service (SMS), multimedia messaging service (MMS), browser, calendar and address book applications, such that a user can easily manage information and communications from a single, integrated device. These applications are typically selectively accessible and executable through a user interface that allows a user to easily navigate among and within these applications.
As part of the user interface, certain handheld electronic devices employ a track wheel assembly having a wheel member which rotates in order to permit a user to scroll among and within the applications. In some such track wheel assemblies, the wheel member can be depressed slightly to provide an input which may be employed, for instance, to choose or select an application. Although the track wheel assembly provides variable speed scrolling capabilities proportional to the speed at which the wheel member is rotated, and is thus a relatively fast and efficient way to find and select a desired application, it also suffers from a number of disadvantages perpetrated by the nature of its design.
By way of specific example, without limitation, the wheel member of the track wheel assembly is pivotally disposed within an opening in the housing of the handheld electronic device. A number of gaps thus exist between the wheel member and the edges of the opening. These gaps provide points of entry allowing moisture, dirt and a wide variety of other undesirable matter to enter the device and potentially cause damage, or hinder operability of the device. In order to avoid the foregoing disadvantages, certain other handheld electronic devices have employed a number of directional buttons in an attempt to adequately replace the track wheel assembly. However, although employing such buttons may have reduced the size of the gaps surrounding the wheel member, and thus the problems generally associated therewith, it did not provide the same navigating experience and capabilities users have grown accustomed to with the track wheel assembly. For example, general directional buttons typically allow line by line scrolling by way of single button presses, and also often provide faster scrolling if, for example, the user holds the button down for a predetermined amount of time, but they do not provide the variable, user-controlled speed and operation provided by the track wheel.
There is, therefore, a need for a handheld electronic device having an input apparatus which is capable of substantially replicating at least some of the desirable operating characteristics (e.g., user-controlled variable speed) of a track wheel assembly, and which simultaneously overcomes at least some of the disadvantages associated with the design of the track wheel.
There is also a need for a method of enabling input into the handheld electronic device using the improved input apparatus.